Telephone-transmitter.



PATENTED DEC. '17, 1907.

' H. W. HAPF.

TELEPHONE TRANSMITTBR..,

APPLICATION IILED APR.15,1907.

awuc nvfoz 35-13% flftoznai s.

A dm m ymm c5 a very sensitive instrument is required.

. still more sensitive in action.

UNITED STATES HOWELL W. HAFE, OF RICHMOND HILL, NE\

V YORK, ASSIGNOR TO GENERAL ACOUSTIC COMPANY, A CORPORATION OF NEW YORK.

TELEPHONE-TRANSMITTER.

Specification of Letters Patent.

Patented Dec. 17, 1907.

Application filed April 16.1907. Serial No. 368.286.

To an whom it may concern:

Be it known that I, HOWELL W. HAFF, a citizen of the United States, residing at Richmond Hill, in the county of Queens and State of New York, have invented certain new and useful Improvements in Telephone Transmitters, of which the following is a full, clear, and exact description.

My invention relates to telephone apparatus, particularly a type of very sensitive transmitter adapted to be used with the dictograph, acousticon and other devices where In the patent to Hyde, No. 711,974, dated October 28, 1902, there is described a form of transmitter in which the sound is received around the side edges instead of against the face of a microphone instrument, and subsequently reflected so as to pass into the microphone from the rear thereof. This form of mstrument is found to operate with very great efficiency in practice, the sound being collected and concentrated and in a sense brought to a focus upon the diaphragm by the reflecting surfaces.

. The present invention relates to improvements in the above device by which it is made For this purpose I avail myself of the front surface or wall of the microphone instrument which surface or wall has hitherto not been utilized to take advantage of the sound vibrations striking against it.

With these purposes and objects in view the invention consists in the'features of construction and combination hereinafter set forth and claimed.

In the drawings: Figure 1 is a front or face view of a transmitter embodying the principles of my invention; and Fig. 2 is a transverse sectional view of the same.

Referring to the drawings in which like parts are designated -'by the same reference sign, 1 indicates a cup-shaped body, into the open front of which the sound waves are adapted to enter, the bottom or inner surface of said body being shaped to receive and concentrate the sound waves and finally direct them backward along the 1 axis of the cupshaped body. I 3 indicates a cover or removable front portion of the body 1, and which is provided with an annular series of perforations 4. around its outside edge. The sound enters through these perforations, thepath thereof being indicated by the dotted lines. These features are not broadly claimed in the present application as they were covered in the patent above mentioned.

" The microphone or-soundreceiving instrument is shown at 5, and has a diaphragm 6,

co-acting with the usual carbon block 7, having carbon 'balls 8 in cavities therein. The block 7 is supported by the plate 9 of the microphone.

11 indicates the opening of the microphone casing through which sound waves may enter to impinge against the diaphragm 6.

Any form of sound receiving device or mi crophone may of course be used.

The late 9 of the microphone in accordance with the resent invention is made very thin so as to e ca able of vibrating in the manner of an or inary diaphragm. The cover or front portion 3of the body may be also provided with a large opening 10, directlyopposite said wall or plate 9, although this is not essential, as good results are securedif the cover 10 is left imperforate over the back of the microphone provided it is made of hard rubber or resonant substance.

The importantcharacteristic of the sound receiving device or microphone 5 is that it has, either actually or virtually, diaphragms on opposite sides thereof, between which the usual microphone electrodes are included.

In use, sound waves which are directed towards the transmitter impinge against the diaphragm-wall 9 at the front and against the diaphragm 6 at the rear at substantially the same instant so that pressure from both directions is applied and relieved simultaneously upon the electrodes. In this way the variations of resistance in the circuit are eniphasized to a far greater degree than is the case where a single diaphragm is used, the result being a much more sensitive instrument. I

What I claim, is

In a telephone transmitter, a cup-shaped body having openings near its edges and having its inner surface shaped to receive and concentrate sound waves therefrom, a-nd finally direct them along the axis of the cupshaped body, a sound receiving instrument having a cover or front portion wit a large central opening through which sai sound waves enter, said recelvmg instrument hav' two separate ing a plate deflected at its outsideedges and forming part of the casing of said instrument, lishing micro hone contacts between said 10 said plate being thin and resilient at the midblock and sai last-mentioned diaphragm.

dle portionthereof and constituting a dia- In itness whereof, I subscribe y slgnacure thereto, a diaphragm Within said sound p'hra m, a' carbon block having cavities seture, in the presence of two witnes es. v receiving instrumentand adapted to be vir WEL brated by the sound Waves entering through Witnesses:

7 said lar e central opening, and a plurality of WALDO M. CHAPIN,

carbon alls within said cavities, and estab- JAMES DANTONIO. 

